1. Field of the Invention
The present invention relates to a motor control device, a motor control method, and a computer-readable storage medium.
2. Description of the Related Art
In various types of electric equipment, a position control system or a speed control system, in which a direct-current motor (referred to as a “DC motor” herein after) is used as a driving source, has been conventionally used in an operation unit. For example, in an image formation device such as a printer and an multifunction machine, a control system for feeding back position information and speed information generated from a rotation detection signal (encoder signal) of a motor is used for a drive control of a DC motor used for conveying a paper such as a recording paper and a document to be copied.
As a conventional technique related to the drive control of the above-described DC motor in an image formation device, a technique of Japanese Patent No. 2886534, for example, is known. Japanese Patent No. 2886534 discloses that an abnormality of rotation is detected from an output of an encoder and when an abnormality is detected, a process of turning off a driver of a motor is performed in order to prevent heating or ignition of a motor caused by an abnormality operation, which may occur in a feedback control system for controlling the driving of a servo (DC) motor, from occurring.
However, this type of conventional technique discloses a configuration applicable only for a limited condition that an abnormality detection is performed using an output of an encoder that detects rotation of a motor during phase-locked loop (PLL) control for an operation at a constant speed. Therefore, when a DC motor operates to monotonically increase its rotation speed with time such as an acceleration operation from a stopped state, it is difficult to detect an occurrence of an abnormality which may be a situation that a rotation detection signal is not normally output from an encoder because of a disconnection or a circuit failure, for example. Thus, a breakage of a mechanical system due to its runaway, damage due to motor heating, and the like is unfortunately caused.
Therefore, there is a need to provide a motor control device, a motor control method, and a computer-readable storage medium capable of preventing a damage of a motor driving system due to an abnormality by detecting an abnormality occurring upon a drive control for increasing rotation of a motor with time.